Accession Number:

ADA021947

Title:

Far Infrared and Submillimeter Wave Attenuation by Clouds and Rain

Descriptive Note:

Corporate Author:

RAND CORP SANTA MONICA CA

Personal Author(s):

• Deirmendjian, D.

Report Date:

1975-04-01

Pagination or Media Count:

40.0

Abstract:

Newly determined optical constants for water at far infrared and submillimeter wavelengths are used to estimate water cloud and rain attenuation over the wavelength range between 12 micrometers and 2cm. For this purpose new analytic dropsize distribution models simulating fog, nimbostratus cloud, and rain corresponding to rainfall rates of 10 and 50 mm per hr. are set up. The corresponding volume extinction and absorption coefficients are computed according to polydisperse Mie scattering theory at specific wavelengths and presented in tables and graphically in plots for purposes of interpolation. It is found that cloud extinction may exceed 50 nepers per kilometer in the wavelength region less than or approximately equal to 100 micrometers region whereas for wavelengths longer than 200 micrometers, under near saturated conditions, water vapor absorption should be the dominant attenuator. The results also suggest that, in the presence of non-precipitating water clouds or fog there may be a relative transmission window centered around wavelength 1.3 mm.

Descriptors:

• *ELECTROMAGNETIC SCATTERING
• *FAR INFRARED RADIATION
• *RADIATION ATTENUATION
• *SUBMILLIMETER WAVES
• CLOUDS
• LIGHT SCATTERING
• OPTICAL PROPERTIES
• REFRACTIVE INDEX
• ATMOSPHERIC SCATTERING
• MIE SCATTERING
• RAIN
• RAINDROPS
• FOG
• DROPS
• ABSORPTION
• DISTRIBUTION FUNCTIONS
• ATMOSPHERIC WINDOWS

Subject Categories:

• Optics
• Radiofrequency Wave Propagation

Distribution Statement:

APPROVED FOR PUBLIC RELEASE